The typical manner in which an electrical connection is established between a discrete conductor and a conductive path on a printed circuit board is by having the discrete conductor pass through a hole that is circumscribed by the conductive path. Solder is then applied to this juncture to envelop both the conductor and the surrounding conductive path and thereby electrically connect one to the other.
An example of this type of connection where the discrete conductor is a contact of a connector is disclosed in U.S. Pat. No. 4,186,988 issued to R. J. Kohler on Feb. 5, 1980. As disclosed in that patent, the connector, which is a jack of the type used in telephones, is mounted on an associated printed circuit board by a multiple of cyndrical locking posts. The posts extend downwardly from a surface of the connector that overlies the printed circuit board, and the posts are accommodated by holes in the printed circuit board,
Each post includes an upper portion having a diameter that is slightly less than the diameter of the hole that accommodates it and having a height slightly greater than the thickness of the printed circuit board. In addition, each post includes a lower portion having a diameter somewhat larger than the hole in the printed circuit board. Finally, each post is split longitidinally whereby the sides of the post can be deflected inwardly to permit the lower portion to pass through the accommodating hole and then return to an undeflected state when the upper portion is positioned within the hole. The lower portion of each post thereby serves to secure the connector to the printed circuit board.
Because of tolerance variations in the thickness of printed circuit boards, the height of the upper portion of each locking post has to be slightly greater than the maximum allowable thickness. There is, therefore, some play between the connector and a printed circuit board of lesser thickness. This play is essentially removed when the spring contacts of the connector are soldered to the printed circuit board. Thus, as is typical, the soldered junctions serve to electrically connect and also physically secure the connector to the printed circuit boards.
As a result of the stresses created in performing the securing function and vagaries in the soldering operation, soldered junctions, while generally providing good conductivity, sometimes fail under shock. More significantly, such junctions can sometimes fail in a manner that creates an intermittent open that is difficult to detect. Also of significance in the very competitive world of electronics is that soldering requires an additional processing step that adds to the cost of the product.
For these reasons it is desirable to be able to make a solderless connection to conductive paths on a printed circuit board. A solderless connection, however, relies on intimate engagement in order to obtain the desired conductivity across the interface between the two elements. This intimate engagement is made more difficult by the above described tolerance variations in the thickness of printed circuit boards. Each contact of the component being electrically connected to the printed circuit board must not be stressed beyond its yield point when the associated component is mounted on a printed circuit board of maximum thickness. Yet, each contact must provide the necessary contact force when the associated component is mounted on a printed circuit board of minimum thickness.